Fluid heater apparatus

ABSTRACT

The present invention relates to fluid heater apparatus having a firing wall, a back wall and side walls defining a furnace space. A plurality of fluid heating tubes are disposed in the furnace space and one or more high intensity combustion burners are attached to the firing wall and positioned so that combustion gases produced thereby are directed into the furnace space and caused to circulate around the heating tubes. By the present invention at least one baffle is disposed in the furnace space adjacent to the firing wall defining a secondary chamber in which additional heating tubes are disposed so that combustion gases impinge on the baffle after impinging on the back wall and are caused to recirculate around the heating tubes and then flow through the secondary chamber whereby additional heat is transferred to the fluid being heated.

United States Patent Ebeling Inventor:

Assignee:

Filed:

Appl. No.2

FLUID HEATER APPARATUS Harold O. Ebeling, Tulsa, Okla.

Black, Sivalls & Bryson, Inc.,

Houston, Tex.

Mar. 21, 1975 US. Cl 122/23; 110/49 R; 122/356;

References Cited UNITED STATES PATENTS Kemp 122/356 X Thurley 122/23Zenlner, Jr. et al. 122/356 Ebeling et al 122/356 Dec. 9, 1975 [57]ABSTRACT The present invention relates to fluid heater apparatus havinga firing wall, a back wall and side walls defining a furnace space. Aplurality of fluid heating tubes are disposed in the furnace space andone or more high intensity combustion burners are attached to the firingwall and positioned so that combustion gases produced thereby aredirected into the furnace space and caused to circulate around theheating tubes. By the present invention at least one baffle is disposedin the furnace space adjacent to the firing wall defining a secondarychamber in which additional heating tubes are disposed so thatcombustion gases impinge on the baffle after impinging on the back walland are caused to recirculate around the heating tubes and then flowthrough the secondary chamber whereby additional heat is transferred tothe fluid being heated.

9 Claims, 6 Drawing Figures U.S. Patent Dec. 9, 1975 Sheet 1 of 33,924,574

US. Patent Dec. 9, 1975 Sheet 2 of3 3,924,574

FUEL 6145 US. Patent Dec. 9, 1975 Sheet 3 of3 3,924,574

FUEL GA 5 IF IF 1, J

FLUID HEATER APPARATUS BACKGROUND OF THE INVENTION 1. Field of theInvention The present invention relates generally to improved fluidheater apparatus, and more particularly, but not by way of limitation,to improved heater apparatus of the type wherein hot combustion gasesare caused to circulate around heating tubes disposed within a furnacespace.

2. Description of the Prior Art A great variety of fluid heaterapparatus have been developed and used successfully. One such heaterwhich has proven to be particularly useful in the oil chemical and otherindustries for heating vrious types of fluids is described and claimedin U.S. Pat. No. 2,993,479, assigned to the assignee of this presentinvention. This type of heater is basically comprised of a wallstructure forming a furnace space which contains a plurality of heatingtubes and one or more high intensity combustion burners are connected toa wall of the furnace space. High intensity combustion burners arecharacterized in that substantially complete combustion takes placewithin the combustion chambers of the burners, and as a result, theburners can be mounted in direct communication with the furnace space.An air blower is utilized with the burners so that the products ofcombustion formed by the burners are directed into the furnace spaceunder super-atmospheric pressure and caused to be circulated around theheating tubes therein in a manner such that even connection heating ofthe tubes and the fluid passing therethrough results.

By the present invention an improved fluid heater apparatus of the typedescribed above is provided whereby greater recirculation of thecombustion gases within the furnace space and around the heating tubesresults and a secondary chamber is provided in the furnace spacecontaining heating tubes over which the combustion gases flow therebytransferring additional heat from the combustion gases to the fluidbeing heated.

SUMMARY OF THE INVENTION The present invention relates to an improvedheater apparatus comprising a firing wall, a back wall and side wallsdefining a furnace space. A plurality of fluid heating tubes aredisposed in the furnace space and one or more high intensity combustionburners are attached to the firing wall and positioned so thatcombustion gases produced by the burners are directed into the furnacespace. The combustion gases impinge on the back wall of the furnacespace and circulate around the heating tubes. At least one baffle isdisposed in the furnace space adjacent to the firing wall defining asecondary chamber therewithin between the firing wall and the baffle sothat at least a portion of the combustion gases produced by the burnersimpinge on the baffle after impinging on the back wall and are caused torecirculate around the heating tubes. At least one stack is attached toa side wall of the furnace space communicated with the secondary chamberso that combustion gases are withdrawn from the furnace space throughthe secondary chamber.

It is, therefore, a general object of the present invention to providean improved fluid heater apparatus.

A further object of the present invention is the provision of animproved fluid heater apparatus of the type 2 wherein combustion gasesare circulated within a furnace space whereby maximum utilization of theheat content of the combustion gases is realized.

Yet a further object of the present invention is the provision of animproved heater apparatus wherein increased recirculation of combustiongases around the heating tubes results.

Still another object of the present invention is the provision of animproved heater apparatus including a secondary chamber within thefurnace space having fluid heating tubes disposed therein whereby heatcontained in the combustion gases normally lost to the stack istransferred to the fluid being heated.

Other and further objects of the present invention will be readilyapparent to those skilled in the art upon a reading of the descriptionof preferred embodiments which follows when taken in conjunction withthe accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view partly insection, of one form of the improved heater apparatus of the presentinvention.

FIG. 2 is a front elevational view of the heater apparatus of FIG. 1.

FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 1.

FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 3.

FIG. 5 is a front elevational view taken in cross-section of analternate form of the improved heater apparatus of the presentinvention.

FIG. 6 is a cross-sectional view taken along line 6-6 of FIG. 5.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawings, andparticularly to FIGS. 1 through 4, the improved fluid heater apparatusof the present invention is illustrated and generally designated by thenumeral 10. The apparatus 10 is basically comprised of a rectangularfiring wall 12, a rectangular back wall 14 and four rectangular sidewalls 16 forming a furnace space 18. A plurality offluid heating tubes20 are disposed within the furnace space 18 connected together in aconventional manner by return bends 22. As best shown in FIGS. 3 and 4,the heating tubes 20 are preferably divided into a pair of tube banks 25and 27 positioned on opposite sides of the furnace space 18 so that aspace free of heating tubes is provided between the firing wall 12 andback wall 14 of the furnace space 18. Each of the tube banks 25 and 27includes an inlet connection 24 and an outlet connection 26 passingthrough one of the side walls 16 of the furnace space 18.

The heating tubes 20 are positioned within the furnace space 18 parallelto each other and parallel to two opposite side walls 16 ofthe furnacespace 18. A pair of high intensity combustion burners 30 are attached tothe firing wall 12 positioned on a line intermediate to the side walls16 which are parallel to the heating tubes 20. The term high intensitycombustion burner is used herein to mean any burner apparatus or burnerapparatus in combination with one or more air or com bustion gas blowerswhich is capable of producing hot combustion gases at a relatively highvelocity under super-atmospheric pressure. A particularly suitable typeof high intensity combustion burner which is preferred for use inaccordance with the present invention 3 is described and claimed in US.Pat. No. 3,265,113, assigned to the assignee of this invention.

Each of the high intensity combustion burners 30 includes a combustionair inlet 32 connected to a source of combustion air atsuper-atmospheric pressure such as an atmospheric air blower (notshown), and includes a fuel gas inlet 34 connected to a source of fuelgas. Conventional instruments and controls (not shown) are provided inassociation with the burners 30 so that fuel and combustion air aresupplied to the burners 30 in a substantially stoichiometric mixture.Substantially complete combustion of the mixture takes place within theburners 30 thereby producing relatively high velocity jets of hotcombustion gases which are discharged by the burners 30 into the furnacespace 18 in a direction towards the back wall 14 thereof.

A pair of baffles 36 are disposed within the furnace space 18 adjacentthe firing wall positioned in a plane parallel thereto. Each of thebaffles 36 is rectangular in shape and is sealingly attached, such as bywelding, at one side and the ends thereof to the side walls 16 formingthe furnace space 18. In addition, the baffles 36 are positioned onopposite sides of the burners 30 and are of a size such that the inwardsides of the baffles 36 terminate short of a line intermediate to theside walls 16 which are parallel to the heating tubes 20 thereby forminga rectangular opening running the length of the furnace space 18 abovethe burners 30.

The baffles 36 form a pair of secondary chambers 38 between the firingwall 12 and the baffles 36 on opposite sides of the burners 30. Thelower portions of the tube banks and 27 are disposed within the chambers38 as best shown in FIG. 3. A pair of stacks 40 for withdrawing spentcombustion gases from the furnace space 18 are attached to each of theside walls 16 which are parallel to the heating tubes 20 by way ofconnections 42 disposed therein. The connections 42 communicate with thesecondary chambers 38 so that combustion gases withdrawn from thefurnace space 18 are caused to flow through the chambers 58.

A pair of elongated concave-convex baffles 44 are disposed within thefurnace space 18 and positioned with the concave surfaces thereof facingthe heating tubes 20. The baffles 44 are attached to the side walls 16which are parallel to the heating tubes 20 and to the upper sides of thebaffles 36 in a conventional manner such as by welding. As will beunderstood, the baffles 36 and 44 on each side of the burners can beintegrally formed from single metal plates, or a plurality of metalplates can be used as dictated by good manufacturing techniques.

Referring now to FIGS. 5 and 6, an alternate form of the improved fluidheater apparatus of the present invention is illustrated and generallydesignated by the numeral 50. The apparatus 50 is similar to theapparatus 10 described above, except that the firing wall 52 and theback wall 54 are of circular shape and the side walls are formed of asingle cylindrical wall 56 thereby forming a cylindrical furnace space58.

A plurality of circular heating tubes 60 are disposed within the furnacespace 58 connected together in a conventional manner to form a pair ofhelical coils connected in series and having an inlet connection 62passing through the side wall 56 and an outlet connection 64 passingthrough the back wall 54. A continuous annular baffle 66 is disposedwithin the furnace space 58 adjacent to the firing wall 52 in a planeparallel thereto. The baffle 66 is attached at its outer sides to thecylindrical wall 56 such as by welding. A high intensity combustionburner 68 of the type described above is attached to the firing wall 52at a central position therein so that the opening in the annular baffle66 is positioned above the discharge of the burner 68. The annularbaffle 66 forms a secondary chamber 69 between it and the firing wall 52within the furnace space 58, and four stacks 70 are connected to thecylindrical side wall 56 by way of connections 72 communicating with thesecondary chamber 69.

Preferably, the heating tubes 60 are of a diameter and arranged in amanner so that in cross section, as shown in FIG. 5, the heating tubesare stacked vertically above the annular baffle 66 and a space free ofheating tubes is provided between the firing wall 52 and burner 68 andthe back wall 54 of the furnace space 58. Several of the heating tubes60 are disposed within the secondary chamber 69 formed by the baffle 66.

An annular concave-convex baffle 76 is provided positioned with theconcave surface thereof facing the heating tubes 60 and attached to theside wall 56 and the top side of the annular baffle 66.

OPERATION In operation of the improved fluid heating apparatus 10illustrated in FIGS. 1 through 4, relatively high velocity jets of hotcombustion gases generated by the burners 30 are directed into thefurnace space 18 from the firing wall 12 towards the back wall 14thereof. The jets of combustion gases impinge against the back wall 14and circulate around the heating tubes 20 as shown by the arrows in FIG.3. After impinging on the back wall 14 the combustion gases flow aroundthe heating tubes 20 in a generally downward direction towards thebaffles 44 and 36, and at least a portion of the combustion gasesimpinge on the baffles 44 and 36 causing them to recirculate around theheating tubes 20 in a generally upward direction. The combustion gasesthen change direction and travel downwardly through the space betweenthe baffles 36 and through the secondary chambers 38 wherein they flowover the heating tubes 20 disposed therein. As will be understood, asthe combustion gases circulate around the heating tubes 20 positionedabove the baffles 36 heat is transferred from the combustion gases tothe fluid being heated. Because the combustion gases are caused tocirculate and recirculate around the heating tubes, substantially evenheating thereof takes place resulting in highly efficient heat transferfrom the combustion gases to the fluid being heated. The combustiongases flowing through the chambers 38 flow over and around the heatingtubes 20 disposed therein giving up additional heat to the fluid beingheated. The spent combustion gases are then withdrawn from the chambers38 and the furnace space 38 by way of the stacks 40 connected thereto.

The concave-convex baffles 44 disposed in the furnace space 18facilitate the smooth change in direction of the combustion gasestraveling downwardly and impinging thereon increasing the recirculationof the gases around the heating tubes 20.

The operation of the improved fluid heating apparatus 50 illustrated inFIGS. 5 and 6 is similar to that described above for the apparatus 10.That is, a high velocity jet of combustion gases is generated by theburner 68 and directed from the firing wall 52 towards the back wall 54of the furnace space 58 as shown by the arrows in FIG. 3. The combustiongases impinge against the back wall 54 and circulate around the heatingtubes 60 in a generally downward direction within the furnace space 58.Afterimpinging on the back wall 54 at least a portion of the combustiongases impinge on the baffles 66 and 76 and are caused to recirculatearound'the heating tubes 60 in a generally upward direction. Thehcombustion gases then change direction and flow downwardly around theinner side of the annular baffle 66and over and around the heating tubes60 disposed in the chamber 69 formed thereby. As the combustion gasesflow through the secondary chamber 69, heat is given up to the fluidbeing heated flowing within the heating tubes disposed therein and theresultant spent combustion gases are withdrawn from the chamber 69 andthe furnace space 58 by way of the stacks 70 attached thereto. Theconcave-convex baffle 76 facilitates the smooth change in direction ofthe combustion gases impinging thereon increasing the recirculation ofthe gases around the heating tubes 60.

The combination of increased circulation of combustion gases around theheating tubes disposed within the furnace space of the improved heaterapparatus of this invention and the additional heat transferred from thecombustion gases as they pass through the secondary chamber or chambersprovided in the furnace space bring about a fluid heater apparatus ofhigh heat transfer efficiency.

As will be understood by those skilled in the art, the heating tubesdisposed within the furnace space of the apparatus can be connected inparallel banks, in series or in other flow arrangements as dictated bythe conditions of the fluid to be heated and the heat required to betransferred thereto. In addition, any number of high intensitycombustion burners can be utilized as dictated by the heat releaserequired, etc. Further, more or less stacks than those disclosed can beutilized, and combustion gases can be circulated from adjacent the backwall within the furnace space to a point adjacent the firing wallthereof externally of the furnace space through the use of conduit meansand a combustion gas blower.

Thus, the present invention is well adapted to carry out the objects andattain the ends and advantages mentioned as well as those inherenttherein. While presently preferred embodiments of the invention havebeen described for the purpose of disclosure numerous changes in thedetails of construction and arrangement of parts can be made which willreadily suggest themselves to those skilled in the art. For example, asdisclosed, the furnace space of the heater apparatus can be square,rectangular or cylindrical in shape and the heating tubes can bestraight, circular, formed into continuous helical coils, etc. Sucharrangements are encompassed within the spirit of the inventiondisclosed herein and the scope of the appended claims.

What is claimed is:

1. In a fluid heater apparatus having a firing wall, a back wall andside walls defining a furnace space, a plurality of fluid heating tubesdisposed in said furnace space and one or more high intensity combustionburners attached to said firing wall and positioned so that combustiongases produced by the burners are directed into said furnace space,impinge on said back wall and are caused to circulate around saidheating tubes thereby bringing about the transfer of heat from saidcombustion gases to the fluid being heated, the improvement whichcomprises:

at least one baffle disposed in said furnace space adjacent to saidfiring wall defining a secondary chamber within said furnace spacebetween said firing wall and said baffle so that at least a portion ofsaid combustion gases produced by said burner 'or burners impinge onsaid baffle after impinging on 'said back wall and are caused torecirculate 1 around said heating tubes; and v f at leastone stackattached to said walls defining said furnace space and communicatingwith said secondary chamber so that combustion gases are withdrawn fromsaid furnace space through said secondary chamber.

2; The fluid heater apparatus of claim 1 which is further characterizedto include a plurality of fluid heating tubes disposed within saidsecondary chamber so that combustion gases flowing therethrough flowover and around said heating tubes thereby bringing about the transferof additional heat from said combustion gases to said fluid beingheated.

3. The fluid heater apparatus of claim 2 which is further characterizedto include rectangular walls defining said furnace space with the axesof said heating tubes being parallel to each other and to two oppositeside walls of said furnace space.

4. The fluid heater apparatus of claim 3 wherein said burner or burnersare positioned on a line intermediate to said side walls which areparallel to said heating tubes and said baffle is further characterizedto be comprised of a pair of flat plates sealingly attached to said sidewalls on opposite sides of said line on which said burner or burners arepositioned thereby defining a pair of secondary chambers on oppositesides of said burner or burners.

5. The fluid heater apparatus of claim 4 which is further characterizedto include a pair of stacks attached to each of said side walls andcommunicating with said secondary chambers so that combustion gases arewithdrawn from said furnace space through said secondary chambers.

6. The fluid heater apparatus of claim 2 wherein said firing wall andback wall are circular in shape, said side walls form a cylindricalenclosure thereby defining a cylindrical furnace space, said parallelheating tubes are circular in shape and said baffle is annular in shape.

7. In a fluid heater apparatus having a rectangular firing wall, arectangular back wall and rectangular side walls defining a furnacespace, a plurality of parallel fluid heating tubesdisposed within saidfurnace space positioned parallel to two opposite sides of said furnacespace and one or more high intensity combustion burners attached to saidfiring wall and positioned on a line intermediate to said opposite sidewalls of said furnace space parallel to said heating tubes wherebycombustion gases produced by said burner or burners are directed intosaid furnace space, impinge on said back wall and are caused tocirculate around said heating tubes thereby bringing about the transferof heat from said combustion gases to the fluid being heated, theimprovement which comprises:

a pair of baffles disposed in said furnace space adjacent to and in aplane parallel to said firing wall, each of said baffles being sealinglyattached to one of said opposite side walls of said furnace spaceparallel to said heating tubes thereby defining a pair of secondarychambers on opposite sides of said burner or burners so that at least aportion of said combustion gases produced by said burner or flow overand around said heating tubes thereby bringing about the transfer ofadditional heat from said combustion gases to said fluid being heated.

9. The fluid heater apparatus of claim 8 wherein said fluid heatingtubes are divided into two banks within said furnace space, said banksbeing positioned on opposite sides of said line on which said burner orburners are positioned thereby providing a space free of heating tubesbetween said burner or burners and said back wall whereby saidcombustion gases first impinge on said back wall and then circulatearound said heating tubes.

1. In a fluid heater apparatus having a firing wall, a back wall andside walls defining a furnace space, a plurality of fluid heating tubesdisposed in said furnace space and one or more high intensity combustionburners attached to said firing wall and positioned so that combustiongases produced by the burners are directed into said furnace space,impinge on said back wall and are caused to circulate around saidheating tubes thereby bringing about the transfer of heat from saidcombustion gases to the fluid being heated, the improvement whichcomprises: at least one baffle disposed in said furnace space adjacentto said firing wall defining a secondary chamber within said furnacespace between said firing wall and said baffle so that at least aportion of said combustion gases produced by said burner or burnersimpinge on said baffle after impinging on said back wall and are causedto recirculate around said heating tubes; and at least one stackattached to said walls defining said furnace space and communicatingwith said secondary chamber so that combustion gases are withdrawn fromsaid furnace space through said secondary chamber.
 2. The fluid heaterapparatus of claim 1 which is further characterized to include aplurality of fluid heating tubes disposed within said secondary chamberso that combustion gases flowing therethrough flow over and around saidheating tubes thereby bringing about the transfer of additional heatfrom said combustion gases to said fluid being heated.
 3. The fluidheater apparatus of claim 2 which is further characterized to includerectangular walls defining said furnace space with the axes of saidheating tubes being parallel to each other and to two opposite sidewalls of said furnace space.
 4. The fluid heater apparatus of claim 3wherein said burner or burners are positioned on a line intermediate tosaid side walls which are parallel to said heating tubes and said baffleis further characterized to be comprised of a pair of flat platessealingly attached to said side walls on opposite sides of said line onwhich said burner or burners are positioned thereby defining a pair Ofsecondary chambers on opposite sides of said burner or burners.
 5. Thefluid heater apparatus of claim 4 which is further characterized toinclude a pair of stacks attached to each of said side walls andcommunicating with said secondary chambers so that combustion gases arewithdrawn from said furnace space through said secondary chambers. 6.The fluid heater apparatus of claim 2 wherein said firing wall and backwall are circular in shape, said side walls form a cylindrical enclosurethereby defining a cylindrical furnace space, said parallel heatingtubes are circular in shape and said baffle is annular in shape.
 7. In afluid heater apparatus having a rectangular firing wall, a rectangularback wall and rectangular side walls defining a furnace space, aplurality of parallel fluid heating tubes disposed within said furnacespace positioned parallel to two opposite sides of said furnace spaceand one or more high intensity combustion burners attached to saidfiring wall and positioned on a line intermediate to said opposite sidewalls of said furnace space parallel to said heating tubes wherebycombustion gases produced by said burner or burners are directed intosaid furnace space, impinge on said back wall and are caused tocirculate around said heating tubes thereby bringing about the transferof heat from said combustion gases to the fluid being heated, theimprovement which comprises: a pair of baffles disposed in said furnacespace adjacent to and in a plane parallel to said firing wall, each ofsaid baffles being sealingly attached to one of said opposite side wallsof said furnace space parallel to said heating tubes thereby defining apair of secondary chambers on opposite sides of said burner or burnersso that at least a portion of said combustion gases produced by saidburner or burners impinge on said baffles after impinging on said backwall and are caused to recirculate around said heating tubes; and a pairof stacks attached to each of said opposite side walls of said furnacespace parallel to said heating tubes and communicating with saidsecondary chambers so that combustion gases are withdrawn from saidfurnace space through said secondary chambers.
 8. The fluid heaterapparatus of claim 7 which is further characterized to include aplurality of fluid heating tubes disposed in each of said secondarychambers so that combustion gases flowing therethrough flow over andaround said heating tubes thereby bringing about the transfer ofadditional heat from said combustion gases to said fluid being heated.9. The fluid heater apparatus of claim 8 wherein said fluid heatingtubes are divided into two banks within said furnace space, said banksbeing positioned on opposite sides of said line on which said burner orburners are positioned thereby providing a space free of heating tubesbetween said burner or burners and said back wall whereby saidcombustion gases first impinge on said back wall and then circulatearound said heating tubes.